Takeuchi TB175W, Руководство по ремонту

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HYDRAULIC UNITS
SHUT-OFF VALVES
IV-82
TB175W
OPERATION
The isolation valve prevents the boom or arm being
raised from falling. If the hydraulic hose breaks, the
valve blocks and isolates the hydraulic oil flowing to
the cylinder head.
When the boom or arm is raised, the pressure oil from
the hydraulic pump flows through the port V2 to push
up the check valve (1) and then through the port C2
into the boom or arm cylinder.
When the boom or arm is lowered, the pilot pressure
from the pilot valve (2) is led to the port PDB. The
pilot pressure in the port PDB moves the spool (3) to
the left. The return oil from the cylinder flows from
the port C2 to the passage through the spool (3) and
the check valve (1), the port V2 and into the tank
passage.
The boom or arm does not fall in case of hydraulic
hose breakage, because the oil flow leading to the
boom or arm is blocked and isolated in the passage
through the check valve (1) and the spool (3) if a hose
breaks.